1. Field of the Invention
The present invention relates to a calender with a roll stack of at least two rolls that are supported in brackets in the area of their axial ends and with a connection arrangement such that at least one roll has a fluid connection and at least one roll has a drive connection.
2. Discussion of Background Information
Such a calender is used to glaze a material web, e.g., a paper web. To this end the material web is guided through at least one nip that is formed by two neighboring rolls that are pressed against one another. With a roll stack featuring more than two rolls, there is a correspondingly higher number of nips in which the material web can be acted on.
At least one of the rolls is driven. In modern Janus-type calendars, all the rolls can be driven. The drive of the at least one roll is provided via a face of the roll, i.e., a drive connection is provided in one of the two brackets. This drive connection can feature, e.g., an electric or hydraulic motor that is connected to the roll directly or via a gear unit. As a rule at least the end rolls are embodied as sag compensation rolls. In a sag compensation roll, the roll jacket is supported on a yoke or carrier via hydraulically greased support shoes. A constant feed of hydraulic fluid is necessary here. Lubricating oil must be constantly supplied to the antifriction bearings of the rolls. To improve the surface properties of a paper web, it is customary to heat at least one roll in the roll stack. To this end, a widespread approach is to feed a heat transfer medium, e.g., a hot liquid like water or oil, or steam into the roll. A fluid connection is necessary for the supply of hydraulic fluid, for the supply of lubricating liquid or for the supply of the heat transfer medium, which fluid connection is also arranged in the area of one or even both of the brackets. Such a fluid connection can feature, e.g., a rotary transmission with which it is possible to transfer a fluid from the stationary bracket to the rotating roll.
The danger of damage to components of the calendars increases with calendars operating more and more quickly. For instance, lines can break or bearings can be damaged. This can lead to dangerous situations.